Lots of interesting stuff here, thanks you all :-)
I sag it at school and I want to sing it this year for my Scottish country dancing cronies at their Christmas ceilidh (Scottish style). They all know the tune and the dance - see http://my.strathspey.org/dd/dance/6995/ - but they don't know the song. It'll educate them as well as make them laugh.
What makes it an interesting dance is the ten thingies (bars?) to a formation instead of the usual eight.